Acan looks like a chunk is missing

[sayitfast]

I have had an Acan for a few weeks now.... eats like crazy always looked healthy.

Today I glanced over at it and it looks like a chunk is missing? Looks great other than that... cannot find any parasites around the base.

Before:

After:

Any ideas?

Thanks

 

[Som1else]

Looks like maybe it got stung, Is there anything near it with sweepers?

 

[sayitfast]

Looks like maybe it got stung, Is there anything near it with sweepers?

Ya... there was a hammer coral not far away... argh!!!!

 

[Justfebreezeit]

+1 to sweepers.
Also I caught an emerald crab taking a chunk out of my acan and it looked every similar as well. Healed up fine but just something to consider!